The invention disclosed in this application pertains to the simulation of a physical system for use in the training and study of the operation of the system. It more particularly deals with the simulation of a fluid circulation system of an oil well.
One of the most feared and dangerous conditions in the drilling of an oil well is a blowout. In this condition formation fluid, which can be oil, gas or water, escapes from the oil well directly into the atmosphere in an uncontrolled manner. The force of the escaping fluid can be so great that equipment is destroyed, rig personnel can be injured or killed, and, in the case of oil or gas, uncontrolled fires can result which are difficult, expensive, and hazardous to extinguish.
The initiation of a blowout condition starts with the introduction of formation fluid into the well bore. This normally occurs when the well is being drilled, or during a trip when the drill pipe is being pulled out of the well. This introduction of formation fluid is known as a well kick. If the initiation of a well kick is recognized in its early stages, corrective measures can be taken and the kick can be controlled before a dangerous condition develops.
Unfortunately, indications that a well kick has started can be very subtle, and may not be recognized. Therefore, it is important that drilling personnel be trained in the detection and control of well kicks to prevent blowouts. This is particularly important in offshore drilling operations where, if a blowout occurs, there is no place to go to escape the accompanying destruction and fire.
In the past, drilling personnel have been trained at special wells using actual equipment. Usually a kick of inert gas is introduced into the well through a tubing placed into the well for that purpose. It can be seen that such an installation is expensive, limited to the condition of that well, and requires that the students come to the well location for training. Also, because of the time required to circulate out a kick, the number of students who can be trained is limited.
A drilling well simulator, as reported in the March, 1972, issue of WORLD OIL, has been developed to train drilling personnel in the prevention of blowouts. However, this device is a complicated device which requires an experienced operator to initiate and control the progression of a well kick based on the student's actions by changing at least one parameter at an operator's panel during the training session. In addition, the device is limited, and cannot simulate all well circulation applications.
Computer programs have been written to calculate pressures and volumes in oil wells, but they will not create a real time display responsive to changes of simulated controls, and additionally must be run on large digital computers. Thus they can only be used where computer facilities are available.
The present invention is an apparatus for simulating the circulation system of an oil well and includes: manually adjustable control means for simulating the controls of the circulation system of an oil well; digital, programmable calculating means responsive to the adjustable control means for calculating the fluid pressure at a plurality of points in the circulation system; and display means for displaying the calculated pressures for selected points in the circulation system thereby simulating the operation of the circulation system. The calculator of the invention includes means for automatically calculating the pressure of an intersected formation to include a selected fractional portion of a time dependent, unrelated real number such that a sufficiently high pressure will be simulated in the formation to cause formation fluid to invade the well bore thus providing a well kick.
The display means responds to the invading fluid and the student's adjustment of the control means for simulating the response of an oil well during a well kick. Thus, the invention is capable of being used to train drilling personnel in the operation of a circulation system of an oil well during the normal drilling of an oil well, and also for the well during the receiving of a well kick. If the well kick is not handled properly, the simulator contains warning means to indicate that a blowout would have resulted, or that a physical limit of the system would have been exceeded had the oil well being simulated been operated in a similar manner. By altering the programming of the programmable calculator, the invention may simulate receiving a well kick while making a trip with the drill pipe, or may simulate a circulation system used for treating an oil well, such as in fracturing or acidizing the well.
The invention additionally includes automatic means for randomly simulating the failure of one or more of a plurality of components in the circulation system. The simulated failure may occur either independent from the well kick, or during the course of the well kick in order that the student may be trained in the recognition of a circulation system component failure, and the handling of a well kick in conjunction with a component failure.
The invention provides for the easy change of the data used by the programmable calculator in actual units of measure, and represented by digital values, thus providing a simulator which simulates a particular well and a given configuration of circulation system in that well. This allows the student to be trained to operate a given circulation system in a given well. The invention also provides a simulator which may be used to evaluate the optimum method for the circulation system configuration for a particular application in a particular oil well.
The invention also includes audio means to simulate the sounds of selected components of the circulation system, thereby adding realism to the simulation.
The programmable calculator of the invention includes calculating means which simulate the introduction of formation fluid from the formation into the well bore; and the expansion, if gas, and flow rate of the fluid as it is circulated in the oil well. Calculation means are also included which simulate the introduction of a subsequent volume of formation fluid if the circulation system is not utilized properly in the circulating out of the first volume of fluid.
The invention's use of a digital programmable calculating means provides a simulator which is inexpensive, is compact and portable, and which may be available for other purposes.